Modeling of Precipitation Effects on the Thermomechanical Behavior of NiTi SMA

The effect of precipitation on Ni-rich NiTi Shape Memory Alloys on the thermomechanical properties is investigated. Particulary, the relation between the chemical evolution of the alloy and phase transformation characteristics are studied in order to evaluate the impact on the global mechanical response. The evolution of chemical composition of the alloy is computed using a diffusion law, according to the precipitates population characteristics. The mechanical response is simulated using a Representative Unit Cell which takes into account the structural effect of the precipitates as well as the effect of the composition change. The results show an important effect on the global mechanical behavior even for a small volume fraction of precipitates.